The OTC products being divested include Phillips MOM, Solpadeine, Dequadin, Cartia and Zantac.
The deal follows agreements reached in December 2011 and last month to divest the brands in the US, Canada and in Europe.
The sale is expected to close in Q2 2012, subject to regulatory approvals.
The proceeds from the transaction are expected to be £135m and GSK said these are to be returned to shareholders during this year.
GSK is a research-based pharmaceutical and healthcare company, and Aspen is a supplier of branded and generic pharmaceuticals, as well as consumer and nutritional products.